01 - In a saucepan, whisk together the milk, cocoa powder, sugar, vanilla extract, and salt over medium heat. Stir constantly until the mixture is hot and thoroughly combined, approximately 4-5 minutes. Ensure the mixture does not reach a boil.
02 - Divide the hot cocoa evenly between two heatproof mugs or glasses, filling each about halfway.
03 - Slowly pour 1/2 cup of chilled root beer into each mug. The effervescence will create a frothy layer.
04 - Gently place one scoop of vanilla ice cream atop each float.
05 - If desired, finish with a dollop of whipped cream and a sprinkle of chocolate shavings or sprinkles.
06 - Present immediately with a long spoon and a straw for an optimal experience.